KR20210142569A - ESS, UPS conversion solar power generation system - Google Patents

Abstract

The present invention relates to a method for replacing an emergency generator by switching to an uninterruptable power supply (UPS) when insufficient charging is expected in a consumer using an energy storage system (ESS), and a system including the same, and more particularly, to a system that replaces an emergency generator or the like through ESS/UPS switching, solar power generation, and grid connection. According to the present invention, the system includes: an ESS that stores a power provided from a solar panel or provides the stored power to a load; a circuit breaker disposed between a power grid and the ESS; a non-contact transfer switch for switching a power line; a monitoring unit for measuring state information of the grid; and a control unit for receiving the measured state information from the monitoring unit, and controlling a mode of the circuit breaker and a device, wherein the control unit determines an operating state of the grid based on the state information to provide the power to the load when the ESS is in a normal charging state, and to switch to a UPS mode and switch the line to the grid when the ESS is in an insufficient power expectation state so as to provide the power stored in the ESS to the load when an accident or a problem occurs in the grid.

Description

Energy storage system (ESS), uninterruptible power supply (UPS) conversion solar power generation system {ESS, UPS conversion solar power generation system}

The present invention relates to a photovoltaic generator that can be used by switching an uninterruptible power supply mode (UPS (Uninterruptible Power Supply) MODE) and an energy storage system mode (ESS (Energy Storage System) MODE) and a system including the same.

An energy storage system is a system that increases energy efficiency by storing produced power in each linked system including a power plant, substation, and transmission line, and then selectively and efficiently using it when power is needed.

The energy storage system can lower the power generation unit cost and reduce the investment and operation cost required for power facility expansion, thereby reducing the electricity rate and saving energy when the overall load factor is improved by leveling the electric load with large fluctuations by time and season. can do.

Such an energy storage system is installed and used in power generation, transmission and distribution, and consumers in the power system. Frequency regulation, stabilization of generator output using new and renewable energy, peak shaving, and load leveling , emergency power supply, etc.

Energy storage systems are largely divided into physical energy storage and chemical energy storage according to storage methods. For physical energy storage, there is a method using pumped water power generation, compressed air storage, flywheel, etc., and for chemical energy storage, there is a method using a lithium-ion battery, a lead-acid battery, or a Nas battery.

On the other hand, in the case of an energy storage system (ESS) installed in a conventional photovoltaic generator, when a shortage of stored power occurs, a method of supplying power to a bypass line (system) or an emergency generator is adopted.

That is, the energy storage system has only performed an auxiliary role for power stabilization of the power system, and there is a problem in cost and energy efficiency by separately operating a bypass line and an emergency generator.

If the energy storage system (ESS) has a problem with the power supply on the bypass line (system) side while it is switched to the bypass route (system) due to insufficient charge, even if the energy storage system (ESS) is installed Power supply problems may occur on the consumer side.

Referring to FIG. 1 , a conventional energy storage system (ESS) includes a system 300 (the bypass), an emergency generator 200, an energy storage system (ESS) 100 and a plurality of loads L1 (500). ), L2 (510)) is electrically connected.

When insufficient charging occurs in the energy storage system (ESS) 100 , the first circuit breaker 130 is cut off, and the second circuit breaker 230 or the third The circuit breaker 330 is opened.

In general, in most cases, only one of the system 300, the bypass (Bypass) and the emergency generator 200 is installed. When an accident occurs, a power outage occurs, and a momentary power outage may occur in the emergency generator 200 due to the start-up time.

That is, an additional accident occurred in the system 300 or the emergency generator 200 in the state in which the second circuit breaker 230 or the third circuit breaker 330 was opened due to insufficient charging amount in the energy storage system (ESS) 100 . In this case, the system 300 and the emergency generator 200 supply power to a plurality of loads L1 ( 500 ), L2 ( 510 ), which causes the emergency generator 200 or the system 300 to use power. This can lead to additional cost and power quality problems.

In addition, since it is difficult to frequently check whether the system 300 and the emergency generator 200 are malfunctioning in normal times where the energy storage system (ESS) 100 is used, the amount of charge of the energy storage system (ESS) 100 decreases. When a problem occurs in the power supply and demand, when a problem occurs in the system 300 and the emergency generator 200, there is a problem in that the power supply and demand of the customer-side loads (L1 (500), L2 (510)) is disrupted.

Afterwards, in the case of a system that automatically switches to the energy storage system (ESS) 100 when the state of charge in the energy storage system (ESS) 100 becomes normal, problems such as noise and output instability occur during switching.

In addition, in the case of an energy storage system (ESS) coupled to a photovoltaic generator, charging is possible only through a solar panel and a charger (AC to DC) that converts alternating current to direct current.

In the case of a charger (AC to DC) that converts AC to DC, it is used to reduce noise and output instability generated during line switching, and power loss occurs due to poor efficiency. There is a problem in that the amount of charge through a charger (AC to DC) that converts alternating current to direct current (AC to DC) increases, such as in winter when sunlight is not good, and during the rainy season, such as an increase in power loss.

The present invention blocks the connection of the energy storage system (ESS) when the problem of insufficient charging power is expected, such as in the winter when sunlight is not good, the rainy season, etc., and the ESS replaces the role of an emergency generator. The purpose of this is to avoid problems such as noise and output instability during switching by changing the device (UPS) mode, and to reduce power loss caused by using a charger (AC to DC) that converts AC to DC.

In addition, the present invention calculates and predicts the load by operating the energy storage system (ESS) as a current source in normal times, and operates by changing the uninterruptible power supply (UPS) mode when the usage is high, and when the system is disconnected, the ESS is an emergency generator It aims to provide an emergency generator replacement system that can smoothly maintain power supply by replacing it.

In addition, the present invention aims to be used alone as a UPS in a situation where there is no solar panel, and as an ESS in a place where there is no system, if necessary.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. Moreover, it will be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In order to achieve the above object, an uninterruptible power supply (UPS) and an energy storage system (ESS) are integrated, and between the system and the grid that stores the power provided through the solar panel and provides the stored power to the load. In order to achieve the above object, an uninterruptible power supply (UPS) and an energy storage system (ESS) are integrated, and between the system and the grid that stores the power provided through the solar panel and provides the stored power to the load. A circuit breaker arranged, a monitoring unit measuring the state information of the system, and a control unit receiving the state information measured from the monitoring unit and controlling operations of the circuit breaker and the ESS and the UPS, the energy storage system When the (ESS) is in a normal charging state, it is controlled to provide power to the load entirely, and when the battery is reduced below the set power and a shortage of charge is expected, the system supplies power to the load in order to use the ESS as an emergency generator. Switch to UPS mode, which is the provided method.

The state information includes voltage and current measured from the grid and photovoltaic equipment, and the controller compares the state information with a preset reference value (voltage of the battery) to determine and control the operation state of the system. have.

The state of charge of the energy storage system (ESS) is determined to be the normal state when the state information is within a preset reference range, and when the state information is less than or greater than the preset reference range, it is expected to be undercharged or overcharged. can be judged.

When the connection between the system and the consumer side is cut off in the UPS mode, the control unit may control the ESS to operate at the operating voltage and operating frequency when the system operates in a normal state.

In order to achieve the above object, the present invention provides a step of measuring the state information of a system electrically connected to an ESS (Energy Storage System), and the operation of a circuit breaker disposed between the system and the ESS using the measured state information. controlling, and determining the operating mode of the ESS based on the operating state of the circuit breaker.

According to the UPS and ESS conversion system of the present invention as described above, in a normal state, the ESS is independently driven as a current source to supply power to the load, and in an expected state of insufficient charging, the power supply is smoothly supplied by power supply through the system. It has the advantage of being able to solve problems that may occur in the event of a system accident by maintaining it and using the ESS as an emergency generator.

In addition, the UPS and ESS conversion system of the present invention can also improve power supply stability and power quality on the consumer side in case of a grid accident by switching power supply lines.

In addition, the control unit of the UPS and ESS conversion system of the present invention supplies power from an energy storage system (ESS) according to a command, thereby securing a fast response speed in case of a system accident and can easily check the power flow in the system unit.

In addition, by replacing the emergency generator, it is easy to maintain and manage the equipment, and it is possible to reduce various resources and costs required to manage the system.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 is a diagram showing the operation of the ESS in the case of a conventional ESS discharge and system power supply problem.
2 is a view showing the switching operation of the energy storage system mode (ESS) and the uninterruptible power supply mode (UPS MODE) when the ESS of the present invention is expected to lack charging power.
3 is a flowchart illustrating a method in which the ESS, UPS conversion solar power generation system of the present invention is driven.
4 is a flowchart illustrating a method of switching a line to an ESS when a grid outage occurs in the UPS mode of the present invention.
5 is a view showing the ESS, UPS conversion solar power generation system including the solar panel and the emergency charger of the present invention.

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but identical or similar components are given the same and similar reference numerals, and overlapping descriptions thereof will be omitted. The suffixes "module" and "part" for the components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have a meaning or role distinct from each other by themselves. In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in the present specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed herein is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present invention , should be understood to include equivalents or substitutes.

Terms including an ordinal number, such as first, second, etc., may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is mentioned that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as "comprises" or "have" are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

First, Figure 2 is a view for explaining each configuration of the ESS, UPS conversion system according to an embodiment of the present invention.

Referring to FIG. 2 , the KEPCO system 300 and the ESS 100 are connected to the respective monitoring units 150 and 350 , and a control unit for reading the values determined by the monitoring units 150 and 350 , in the control unit Based on the read value, it may be configured to include a contactless transfer switch 130 and 330 for controlling the line, and a blocking unit for circuit protection.

The DC blocking unit of the circuit protection circuit breaker may include at least one DC circuit breaker for protecting the load and internal circuits by blocking the abnormal UPS module from the load when an abnormality occurs in the ESS module.

On the other hand, the AC breaker blocks the commercial power when an abnormal condition such as a short circuit occurs from the alternating current (AC: alternating current) input from the commercial power source to protect the internal circuit from overcurrent or arc. It may include at least one AC circuit breaker.

Meanwhile, the battery breaker may include at least one DC breaker for blocking the battery when an abnormal condition occurs in the battery to protect the internal circuit from overcurrent or arc.

Meanwhile, the AC or DC current circuit breaker included in the DC blocking unit, AC blocking unit, or battery blocking unit may be configured to include at least one MCCB (Molded Circuit Breaker) or ACB (Air Circuit Breaker). In the description, when each of the blocking units is on, the circuit is closed to connect the converter, and when the circuit is turned off, the circuit is opened to short-circuit or block the circuit.

First, Figure 3 is a flow chart explaining the way the ESS, UPS conversion solar power generation system of the present invention is driven.

The 25% portion of the amount of power in Fig. 3 is for illustration, and can be changed in the control unit and can be configured to include a control unit that can be automatically controlled according to the customer-side load situation.

First, FIG. 4 is a flowchart illustrating a method of switching a line to an ESS when a grid outage occurs in the UPS mode of the present invention.

The notification generation part of FIG. 4 includes a method of generating a notification in various ways, such as an alarm sound, a warning light, a mobile pop-up notification, and a text message.

5 is a view for explaining each configuration of the ESS, UPS conversion solar power generation system according to an embodiment of the present invention.

Referring to FIG. 5 , the solar panel controller 420 that receives direct current (DC) from the solar panel 400 and converts it into a battery charging voltage, the solar panel controller 420 outputs A monitoring unit 150 for checking voltage and current values, a battery 460 to receive a charging voltage through the solar panel controller 420, and an inverter 480 for using an AC (Alternating Current) load, The battery 460 may be configured to include an emergency chargeable battery charger 470 when a problem occurs, and the aforementioned AC breaker for accident propagation and internal circuit protection before supplying power to the load.

The first circuit breaker 130 and the third circuit breaker 330 must include an interlock device to prevent simultaneous input of the KEPCO system and the ESS to the AC circuit breaker.

At least one DC-DC converter between the battery 460 and the control unit may be included in order to secure power for operation of the control unit, and a battery blocking unit for opening the circuit may be included.

The above detailed description should not be construed as restrictive in all respects, but rather as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are included in the scope of the present invention.

100: ESS 130: 1st circuit breaker (solid-state transfer switch) 150: ESS monitoring unit
200: emergency generator 230: second breaker (solid-state transfer switch)
250: emergency generator monitoring unit
300: system 330: third circuit breaker (solid-state transfer switch) 350: system monitoring unit
400: solar panel 420: solar panel controller
460: battery 470: battery charger 480: inverter
500: load 1 510: load 2

Claims (4)

ESS (Energy Storage System) that stores the power provided from the system or provides the stored power to a load;
a circuit breaker disposed between the system and the ESS;
a monitoring unit for measuring the state information of the system; and
Receiving the measured state information from the monitoring unit, and controlling the operation of the breaker and the ESS
including a control,
The control unit determines the operating state of the system based on the state information,
When the system is in a normal charging state, the consumer side controls the ESS to exclusively provide power to the load,
UPS, ESS conversion system that receives power from the system when the system is in an expected state of insufficient charge and provides the power stored in the ESS to the load when there is a problem in the system According to claim 1,
The status information is
Including voltage and current information measured from the system,
The control unit compares the state information with a preset reference value to determine the operating state of the system, UPS, ESS conversion system According to claim 1,
The operating state of the system is,
If the status information is within a preset reference range, it is determined as the normal state, and when the status information is less than or exceeding the preset reference range, the UPS, ESS conversion system that is determined to be the under-charged or overcharged state According to claim 1,
UPS, ESS conversion system in which the control unit controls the ESS to operate at the operating voltage and operating frequency when the system operates in a normal state when the connection between the system and the consumer is cut off.

Images